The present invention relates to impact power tools and, more particularly, to an improved hand-held impact power tool for delicate hand engraving and stone setting in the hand engraving and jewelry fields.
An impact power tool is known from my earlier U.S. Pat. No. 6,095,256, to Lindsay, which may be used for engraving, carving and delicate stone setting operations.
Although the known impact power tool mentioned above provides improved control of delicate hand-working operations not previously available, it would be desirable to provide an impact tool with a feature that will provide greater ease of use. A known embodiment disclosed in my earlier U.S. Pat. No. 6,095,256, to Lindsay, uses a feature to adjust the impacting characteristics of the tool. This feature is beneficial to users, however modifying this impacting adjustment takes valuable time from the jeweler or engraver, as two setscrews need to be loosened before the user can begin to adjust the tool. The feature utilized the end of a screw for the impact location within the bore of the tool. When the user adjusts this screw and thus the location of impacts, it allows the piston to enter into the front chamber letting more or less exhaust be released. It allowed more or less air pressure stored in the rear chamber to pass through the piston to the front chamber and to the atmosphere. When more air pressure was relieved from the rear chamber the piston was allowed to make a longer return stroke and thus harder impacts in the forward stroke. If this feature could adjust a floating tool holder or anvil with a rotating barrel on the outside of the handpiece it would make the impact tool more user friendly.
Floating tool holders and anvils in hand held impact power tools are not new. U.S. Pat. Nos. 6,085,850, 5,803,183, 5,449,044, and 4,030,556, all to Phillips, utilize rubber o-rings to float an anvil that attaches to a tool holder. U.S. Pat. No. 6,021,574, to Murray, utilizes rubber o-rings to float a tool holder. Owner""s manual titled GRS Tools 901 Handpiece written by Glendo Cooperation, page 3, depicts an impact tool using o-rings to float an anvil. O-rings used in these configurations will return the tool holder or anvil to its original location after each impact or blow of the piston. What is needed to construct a more user friendly length of stroke adjustment than what is depicted in my earlier impact tool U.S. Pat. No. 6,095,256 is a way for the user to manually, yet quickly, adjust the anvil and/or tool holder and thus alter the impacting location.
In my earlier invention U.S. Pat. No. 6,095,256, an impact tool was depicted with a manual adjusting length and speed of piston stroke mechanism. The present invention includes a more convenient mechanism to adjust this length and speed of piston stroke. The mechanism includes a rotating barrel protruding around the outside diameter of the body of the impact power tool that may be turned for adjusting a floating tool-holder. This will alter the distance between the annular ring within the bore and the impact location of the piston. Adjusting how far the piston enters into the front chamber of the handpiece will determine how much pressure in the rear chamber is relieved on each piston forward stroke. The amount of pressure relived at the end of the forward stroke will determine the length of the return piston stroke and thus the overall power of the impacting tool. A rotating barrel around the outside of the tool will provide a tool that is more versatile and easily altered by the user to his or her liking.
It is also an object of this invention to provide a simplified mechanism to adjust the stroke length that is inexpensive to manufacture and assemble.